ELEMENTS OF MATERIA MEMCA.
592
and bran ( furfur tri(ici). The same wheat yields several qualities otflour, distinguished as firsts, or fine flour; seconds; and thirds , ox mid-dlings.
Composition. —The following are the constituents of several kinds olwheat (Vauquelin, Journ. Pharm. viii. 358).
Wheat.
OdessaHardWheat. |
Odessa
Soft
Wheat.
Ditto.
Ditto.
Ditto, of goodquality, usedin publicestablishments.
Ditto,
inferior
kind.
7149
56-5
62*00
70*84
72*00
72*8
71*2
67-78
10-96
14-55
12*00
12*10
7*30
10*2
10*3
9*02
Su^ar....
4*72
8*48
7*56
4*90
5-42
4*2
4*8
4*80
332
4*90
5*80
4*60
3*30
2*8
3*6
4*60
2*30
1*20
200
Water....
10-00
12*00
10-00
8*00
12 00
10*0
8-0
12 00
100*49
98*73
98*56
100*44
100*02
1000
979
100*20
The substance commonly termed gluten is a compound of vegetablealbumen, which is insoluble in alcohol, of mucin, soluble in hot alcohol,and of glutin or gliadine, soluble in both hot and cold alcohol.
Chemical Characteristics. — The cold decoction of wheat-flourforms, with tincture of iodine, the blue iodide of starch. If wheat-flourbe made into a paste, with water, and then kneaded under a stream ofwater until the liquid runs off colourless, the residue in the hand i sgluten. The water, on standing, deposits starch ; but retains in solutiongum, sugar, and some phosphatic salts. Nitric acid gives wheat-flour afine orange-yellow colour. Recently-prepared tincture of guaiacum formsa blue colour with good wheat-flour.
Manufacture of Starch. —Starch is procured by steeping wheat-flour in water for one or two weeks, during which time acetous fermen-tation takes place. The acid liquor (sours) is drawn off, and the impurestarch washed on a sieve, to separate the bran. What passes through I sreceived in large vessels, termed frames. Here the starch is deposited-The sour liquor is again drawn off, and the slimes removed from thesurface of the starch, which is to be again washed, strained, and allowedto deposit. When, by these processes, the starch has become sufficientlypure, it is boxed, that is, it is placed in wooden boxes perforated withholes and lined with canvas, where it drains. It is then cut in squarelumps, placed on bricks, to absorb the moisture, and dried in a stove-While drying it splits into prismatic pieces, similar to grain tin, ° rcolumns of basalt. The greater part of the starch used for stiffening lm e ®(called Poland and glaze starch) is coloured blue by finely-powderedsmalt, or by indigo. This is not adapted for medicinal purposes. WhH e(sometimes called French ) starch should he employed. A fine varietyof this is termed patent white starch.
Properties of Starch. —Pure wheat starch ( amylum, L. D ; amylur*ex Tritico hyberno, E.) is white, and almost odourless and tasteless. E x jamined by the microscope, it is found to consist of rounded or spheric®grains, not exceeding the '002 of an inch in diameter. These gr alJ1 ®consist of a membranous coat ( amidon; amylin; tegument of the ferule)enclosing transparent colourless substance (gummy matter; amid tn )'When immersed in cold water, they swell up, but remain entire; 'boiling water, they burst, the gummy matter is dissolved, while tintegument swells up, becomes transparent, and floats. Boiled in wate >